Adam Clarke on Psalms 18:49

WilI I give thanks unto thee - among the heathen - Quoted by St. Paul, Rom 15:9, to prove that the calling of the Gentiles was predicted, and that what then took place was the fulfillment of that prediction.

But there is a sense in which it applies particularly to David, well observed by Theodoret: "We see," says he, "evidently the fulfillment of this prophecy; for even to the present day David praises the Lord among the Gentiles by the mouth of true believers; seeing there is not a town, village, hamlet, country, nor even a desert, where Christians dwell, in which God is not praised by their singing the Psalms of David."